Runoff and infiltration characteristics of pavement structures--review of an extensive monitoring program.

The stormwater runoff and infiltration performance of permeable pavements has been systematically evaluated within an intensive monitoring program. The primary objective of the investigation was to generate a broad database, which enables the development of an advanced simulation module for urban drainage modelling. Over 160 field and lab scale experiments have been completed and analyzed for surface runoff and infiltration characteristics. The test series include several pavement types under various boundary conditions such as diverse precipitation impacts, varying surface slope and layer construction as well as different stages of surface clogging and several base and subgrade layer characteristics. The results represent a reliable and comprehensive database that allows profound conclusions and substantial recommendations.     

Isothiazol-1,1-dioxide – vom Süßstoff zum chiralen Auxiliar in der stereoselektiven Synthese

Isothiazole 1,1-dioxides – From Sweeter to Chiral Auxiliar in the Stereoselective Synthesis This review gives a report of the last ten years on the new synthetic methods, reactions and biological applications of isothiazole 1,1-dioxide derivatives. the formation of monocyclic and heterocyclic annelated isothiazole 1,1-dioxides by oxidation of isothiazoles, cyclocondensation of sulfonamides and cycloaddition of isothiazol-3(2H)-one 1,1-dioxides are discussed in more detail. Furthermore, the preparation of pharmacologically important N-substituted saccharines is reported. New saccharine-derived chiral N-enoyl-and N-acyl-2,3-dihydro-1,2-benzisothiazole 1,1-dioxides serve as advantageous stereoface-directing dienophile and dipolarophile auxiliaries in Diels-Alder-reactions and 1,3-dipolar cycloadditions. Asymmetric alkylations, acylations and aldolizations are also described.     

Reduction of nitrogen dioxide by propene over acidic mordenites: influence of acid site concentration, formation of by-products and mechanism

The reduction of nitrogen dioxide to nitrogen by propene was studied over a variety of acidic mordenite zeolites differing in their Si : Al ratio and thus, in their concentration of acid sites. The formation of by-products was monitored applying an ion–molecule reaction (IMR) mass spectrometer. It was found that at fixed conditions the yield of nitrogen increases with increasing concentration of acid sites, confirming that acid sites are the active catalytic centres in the reaction. Apart from nitrogen and nitric oxide, acrylonitrile and ammonia are formed as nitrogen containing gas-phase products in the reaction. In separate experiments, it was shown that acrylonitrile is hydrolysed by water over the acidic zeolites to yield ammonia and acrylic acid. When acrylonitrile is used as reducing agent for nitrogen dioxide, formation of nitrogen is strongly enhanced in the presence of water. Water also has a promoting effect on the formation of nitrogen in the reaction between nitrogen dioxide and propene. Acrylonitrile and its product of hydrolysis, ammonia, are considered to be intermediates of nitrogen dioxide reduction to nitrogen by propene over acidic zeolites.     

Membrane supported catalytic dehydrogenation of iso-butane using an MFI zeolite membrane reactor

A H₂-selective MFI zeolite membrane has been crystallized as layer on a porous ceramic tube. At 510 °C, this membrane can separate H₂ from iso-butane/iso-butene with mixture separation factors of 70 and H₂ permeances of ca. 1 m³ (STP)/m² hbar. In membrane supported iso-butane dehydrogenation the conversion of iso-butane was increased by almost a factor of 2. However, a detailed analysis of the experiment showed that 2/3 of the conversion increase is based on the dilution of the feed by the sweep gas and 1/3 is due to the H₂ removal.     

Duoplasmatron Ion Sources

A survey on questions related to the production of multiply charged ions with the Duoplasmatron ion source is given. In spite of differences of the multiply charged ion source and the mass separator type, design considerations show that high containment is a common feature to be attained in both subjects. Multiply charged metal ions are produced by material evaporation into the magnetically confined anodic plasma and auxiliary gas feed into the cathode discharge regions. Energy spreads of ion beams from the low and the high arc current source are compared. The Duoplasmatron ion source proves to be a hygieneous source of high containment that permits the production of medium charge states up to 9+ for xenon at modest energy spread and good brilliance of the extracted ion beam in a high current-low voltage discharge mode.